As a catalyst for thinking about what an affective life might be and how such a life might be intimately bound up with its relations to its surroundings or environment, I propose in this chapter to present two different ways of thinking about individuality in Spinoza. I do so in order to draw out what is at stake in a double point of view of the degree of the power to act of a singular thing in Spinoza's Ethics. Sometimes this power to act seems to be fixed to a precisely determined degree, whereas sometimes it seems to admit a certain degree of variation. The problem of how to resolve this apparent contradiction has generated varying interpretations among scholars in Spinoza studies, including Martial Gueroult (1974), Gilles Deleuze (1992), Pierre Macherey (1995), and Charles Ramond (1995). The problem cannot be addressed in isolation from two other equally perplexing questions: whether the essence of a singular thing remains fixed or should be understood to be variable; and whether the conatus, as the expression of the power to act of a singular thing, should be understood to remain fixed or to be variable. These three questions are related because the three aspects of Spinoza's philosophy with which they deal – the power to act, modal essence, and conatus – are intimately intertwined, the interpretation of one having a bearing on the interpretation of the others. For a more precise understanding of these different ways of variation, and to render them compatible with each other, it is necessary to commence with the question of the variation of the essences of singular things. Certain interpreters, such as Gueroult, consider these essences to be situated between a ‘minimum’ and a ‘maximum’, and that it is only above or below this range that a rupture occurs in an individual's identity, resulting in a change of the individual's structure and therefore of its nature (Gueroult 1974: 351).

In Quantité et qualité dans la philosophie de Spinoza, by contrast, Charles Ramond argues that the essence of a singular thing is determined by a ‘precise relation’ of movement and rest, or by a quantum of the power to act of the conatus, and all variation is prohibited, since any augmentation or diminution of this power to act would create another individual.